1. Field of the Invention
The present invention relates to an organopolysiloxane, a temporary adhesive composition containing the organopolysiloxane, and a method of producing a thinned wafer using the same.
2. Description of the Related Art
Three-dimensional semiconductor packaging has become indispensable, so as to realize more increased densities and more increased capacities. The three-dimensional semiconductor packaging technique is a semiconductor fabricating technique configured to thin a single semiconductor chip, and to stack such chips in a multi-layered manner while wire-connecting them with one another by through silicon vias (TSV). Required for realizing such a technique are a step for thinning a substrate formed with a semiconductor circuit by back-surface grinding, and an electrode forming step for forming electrodes and the like including TSV on the back surface. Conventionally, in the back-surface grinding step of a silicon substrate before the electrode forming step, it has been typical to apply a protective tape onto a surface of the silicon substrate opposite to the surface to be ground, thereby avoiding wafer damages upon grinding. However, such a tape adopts an organic resin film as a base material thereof, so that the film is unsuitable for conducting a wiring layer forming process at a back surface of the silicon substrate because the tape is flexible but is insufficient in strength, heat resistance.
As such, there has been proposed a system configured to join a semiconductor substrate via adhesive to a supporting substrate made of silicon, glass, or the like, in a manner to be sufficiently durable against a back-surface grinding step and a back-surface electrode forming step. To be important at this time is an adhesive upon joining both substrates to each other. This adhesive is required to possess an adhesiveness of joining the substrates to each other without gaps therebetween, and a sufficient durability to be durable against subsequent processes, as well as such an ability to finally allow the thinned wafer to be easily peeled from the supporting substrate. In this way, this adhesive will be called as a “temporary adhesive”, because the same is to be peeled finally.
As known temporary adhesives and peeling methods therefor, there have been proposed up to now: a technique configured to irradiate a light of high intensity to an adhesive containing a light-absorbing substance so as to decompose an adhesive layer to thereby peel the adhesive layer from a supporting substrate (Japanese Patent Application Laid-Open Publication No. 2004-64040); and a technique configured to adopt, as an adhesive, a heat-meltable hydrocarbon-based compound, in a manner to conduct joining and peeling in the heated and melted state thereof (Japanese Patent Application Laid-Open Publication No. 2006-328104). The former has been problematic, due to necessity of an expensive apparatus such as laser and the like, and due to an extended processing time per one substrate. Further, although the latter is convenient since controlling is conducted by heating only, thermal stability is insufficient at high temperatures exceeding 200° C., thereby resulting in narrowed applications of processes.